Flexible abrasive disc



Nov. 21, 1967 R. ZANE 3,353,308

FLEXIBLE ABRAS IVE DI S C Filed May 8, 1964 I NVENTOR ATTORNEYS UnitedStates Patent 3,353,308 FLEXIBLE ABRASIVE DISC Riccardo Zane, ViaCarducci 5, Cinisello Balsamo, Mailand, Lombardy, Italy Filed May 8,1964, Ser. No. 366,119 Claims priority, application Italy, June 4, 1963,11,973/ 63 2 Claims. (Cl. 51-397) There are known abrasive discsconsisting of a round plate of flexible material, e.g. vulcanized fiberor the like, on one face of which is applied a layer of abrasivematerial. Such abrasive discs are used as front wheels for the honing ofsurfaces, especially of curved and in any case non-planar surfaces, andthe flexibility of the disc enables the performance more easily andthoroughly of said honing operation, inasmuch as the abrasive discadapts itself to the surface to be machined.

In the known abrasive discs, the flexibility is very i-mperfect because,although it is very good for the supporting round plate, it isconsiderably reduced by the abrasive layer applied on it. If thethickness of said layer is substantial, the disc is hard and brittle,whereas, if it is thin enough to accompany to a great extent the flexingof the supporting disc, the life of the abrasive disc is exceedinglyshortened.

Furthermore, in the known abrasive discs the adhesion of the abrasivelayer to the supporting round plate is very poor, so that thedeflections to which the disc is subjected result in said layer fallingoff, and the disc is used up rapidly.

It should also be added that said discs are subject to overheating whichis very harmful to the supporting round plate but still more so to thematerial that is being machined which, in many instances, e.g. when itis thin plate, may be irredemiably damaged. The object of the presentinvention is the provision of a flexible abrasive disc which does notsuffer from the above mentioned inconveniences and which exhibits a muchgreater flexibility than the known discs, both owing to its intrinsicstructure and on account of the production method: furthermore, it showsan excellent adhesion of the abrasive layer to the supporting roundplate, which makes possible a long life, even if the disc is made toperform particularly intense and heavy duty.

Another important advantages of this abrasive disc appears from the factthat, under the same working stress, its heating is very low, comparedto the known discs, so that most of the inconvenience arising from saidexcessive heating of the known discs are eliminated.

The following description is made with reference to the attacheddrawings illustrating diagrammatically the abrasive disc.

FIG. 1 shows the flexible round plate acting as a support, seenfrontally.

FIG. 2 is its diametral section.

FIGS. 3 and 4 are similar views of the disc formed by said round platecoated with abrasive material.

FIG. 5 is a greatly enlarged fragment of a section of the disc.

FIG. 6 is a variant of FIG. 5.

With reference to the above listed drawings:

3,353,308 Patented Nov. 21, 1967 For the manufacture of the abrasivedisc according to the invention, there is initially used a flexibleplate 1 which may be made up of various materials, depending on theapplication requirements, e.g. vulcanized fiber or other materials inlamellar form, more or less similar to one another: the plate isobtained by a shearing of the laminate, and is subjected to a checkingor punching 2 following which its surface to be covered with abrasivematerial is deeply knurled with a 'beehivelike pattern (FIG. 5) andpossibly presents also very small diameter holes 2 (FIG. 6) going fromone face of the plate 1 to the opposite one. This punching forms amultiplicity of indentations confronting said abrasive material andserves essentially the purpose of increasing and better shaping thesurface to which must adhere the abrasive material which, in the case ofFIG. 6, penetrates into the small holes.

This plate receives also larger diameter perforations 3', e.g. of 5 to30 mm. and, moreover, a subsequent sandblasting of the surface on whichthe abrasive will be applied.

The plates so shaped are covered, on the face so prepared, with a layer4 of adhesive material, preferably a liquid synthetic resin, and overthe adhesive layer is spread the abrasive 5.

The excess of abrasive is removed, the plate is again covered with theadhesive material, which for-ms a new layer 40, then again with abrasive50, and so on till a predetermined number of abrasive layers: 5505'-5"separated from one another by as many very thin layers of adhesivematerial: 4-40-4'-4" is formed.

At this point the plate with its layers of adbrasive is subjected to aslight impression in order to conform its surface to more or less spiralradial grooves 6. In some special cases, however, this compression maybe a real pressing, when it is deemed necessary to compress the wholeabrasive layer. Subsequently the abrasive disc is placed in an oven forthe drying and polymerizing of the resin that constitutes the adhesivematerial.

It should be noted that the preforations 3, in addition to improving theadhesion of the abrasive layers to the plate, with the penetration ofsaid layers against their edges, make the disc much more flexible.

It should also be borne in mind that these perforations, with theircontour-as, for that matter, also the spiral groovings6 increase thenumber of rakes and therefore the abrasive effectiveness of the disc.

Moreover, these holes and groovings present an advantage in that theyact as passages for the disposal of waste particles, and in that theyprovide a ventilation which cools the machining area, thereby improvingthe effectiveness of the machining and the possibility of its beingaccelerated without the risk of an overheating of the piece.

I claim:

1. A flexible abrasive disc comprising a known lamellar, flexible,nonmetallic supporting round plate, and a substantial layer of abrasivematerial supported by said round plate, said abrasive layer being madeof a plurality of thin and uniform alternately superposed coatings ofadhesive material and abrasive granules, said round plate having amultiplicity of indentations on its side confronting said abrasivematerial.

2. A flexible abrasive disc as claimed in claim 1, Wherein each saidcoating of abrasive granules comprises substantially all the abrasivegranules that can be held on said round plate by the underlying coatingof adhesive material.

References Cited UNITED STATES PATENTS Martin et a1 51407 4 Fuller 51395Reidenbach 5 1395 Hurst 51397 X Dyar 51397 Simpson 51397 Williamson51293 Barclay 51293 Melton et a1 118-308 Heck 118308 FOREIGN PATENTSFrance.

ROBERT C. RIORDON, Primary Examiner.

15 D. G. KELLY, L. S. SELMAN, Assistarvt Examiners.

1. A FLEXIBLE ABRASIVE DISC COMPRISING A KNOWN LAMELLAR, FLEXIBLE,NONMETALLIC SUPPORTING ROUND PLATE, AND A SUBSTANTIAL LAYER OF ABRASIVEMATERIAL SUPPORTED BY SAID ROUND PLATE, SAID ABRASIVE LAYER BEING MADEOF A PLURALITY OF THIN AND UNIFORM ALTERNATELY SUPERPOSED COATINGS OFADHESIVE MATERIAL AND ABRASIVE GRANULES, SAID ROUND PLATE HAVING AMULTIPLICITY OF INDENTATIONS ON ITS SIDE CONFRONTING SAID ABRASIVEMATERIAL.